Interpretive Summary: The narrow genetic base of cultivated sunflower has been broadened by the infusion of genes from the wild species, which have provided a continued source of agronomic traits for crop improvement. The genus Helianthus comprises 51 species (14 annual and 37 perennial), all native to North America. However, wild sunflowers have been inadvertently and intentionally introduced into several countries where they have become naturalized, most notably in Australia, Argentina, and southern Europe. The distribution of the wild naturalized sunflower species in Australia occurs primarily within the states of Queensland, New South Wales, Victoria), South Australia, and West Australia. Since these species have been naturalized in Australia, the possibility exists that they may have traits distinct from their North American progenitors due to the different environments, diseases and insect pests. Currently there are no collections of wild sunflower from Australia in the USDA-ARS National Plant Germplasm System (NPGS) sunflower germplasm collection. This germplasm would greatly increase the available genetic diversity for these species from outside of North America. The objective of this exploration was to collect achenes (3,000 achenes per population) from as many populations as possible of wild annual sunflower and cucumber leaf sunflower and make them available for future research and improvement of cultivated sunflower. The Australian exploration took place from February 22 through March 14, 2007. It covered 6,250 miles in the states of Queensland, New South Wales, Victoria, South Australia, and West Australia. Five days were spent exploring WA. In spite of the extreme drought, 14 populations of naturalized wild annual sunflower were collected. Six days were spent exploring South Australia, New South Wales and Victoria. These states were especially hard hit with drought, but 21 populations of naturalized wild annual sunflower were collected. An exploration to Queensland, which was also suffering from extreme drought, resulted in the collection of two populations of wild naturalized wild annual sunflower and two populations of cucumber leaf sunflower. The wild species germplasm collected will be evaluated for oil concentration and fatty acid composition, as well as screened for various diseases and insects as a potential source of genes for the improvement of cultivated sunflower. The origin of the naturalized populations of wild sunflower in Australia is still open for discussion. The species found there are commonly grown in gardens as ornamental flowers. It is also possible that the seed was inadvertently introduced in imported forages, or possibly mixed in bird seed. Currently, the time of the introduction of the wild species into Australia is not known. Future genetic population studies may help to answer that question.

Technical Abstract:
The narrow genetic base of cultivated sunflower has been broadened by the infusion of genes from the wild species, which have provided a continued source of agronomic traits for crop improvement. The genus Helianthus comprises 51 species (14 annual and 37 perennial), all native to North America. However, wild sunflowers have been inadvertently and intentionally introduced into several countries where they have become naturalized, most notably in Australia, Argentina, and southern Europe. The distribution of the wild naturalized sunflower species in Australia occurs primarily within the states of Queensland, New South Wales, Victoria), South Australia, and West Australia. Since these species have been naturalized in Australia, the possibility exists that they may have traits distinct from their North American progenitors due to the different environments, diseases and insect pests. Currently there are no collections of wild sunflower from Australia in the USDA-ARS National Plant Germplasm System (NPGS) sunflower germplasm collection. This germplasm would greatly increase the available genetic diversity for these species from outside of North America. The objective of this exploration was to collect achenes (3,000 achenes per population) from as many populations as possible of H. annuus and H. debilis, and make them available for future research and improvement of cultivated sunflower. The Australian exploration took place from February 22 through March 14, 2007. It covered 10,000 km in the states of Queensland, New South Wales, Victoria, South Australia, and West Australia. Five days were spent exploring WA. In spite of the extreme drought, 14 populations of naturalized H. annuus were collected. Six days were spent exploring South Australia, New South Wales and Victoria. These states were especially hard hit with drought, but 21 populations of naturalized wild H. annuus were collected. An exploration to Queensland, which was also suffering from extreme drought, resulted in the collection of two populations of wild naturalized H. annuus and two populations of H. debilis ssp. cucumerifolius. The germplasm collected will be evaluated for oil concentration and fatty acid composition, as well as screened for various diseases and insects as a potential source of genes for the improvement of cultivated sunflower. The origin of the naturalized populations of wild sunflower in Australia is still open for discussion. The species found there are commonly grown in gardens as ornamental flowers. It is also possible that the seed was inadvertently introduced in imported forages, or possibly mixed in bird seed. Currently, the time of the introduction of the wild species into Australia is not known. Future genetic population studies may help to answer that question.